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  "body": "\n## Summary\n\nIn graph theory, a **universal vertex** is a vertex of an undirected graph that is adjacent to all other vertices of the graph. It may also be called a **dominating vertex**, as it forms a one-element dominating set in the graph. A graph that contains a universal vertex may be called a **cone**, and its universal vertex may be called the **apex** of the cone. This terminology should be distinguished from the unrelated usage of these words for universal quantifiers in the logic of graphs, and for apex graphs.\n",
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